Herpes simplex virus 2 (HSV-2) is a major cause of genital ulcer disease, a co-factor for HIV-1 transmission, and causes severe neonatal disease. CD4 T-cells are an important part of the host response. They are protective in animal HSV-2 challenge models, can kill HSV-infected cells, secrete antiviral cytokines, and provide help for antibody and CTL effectors. Current vaccines are partially effective only in HSV-uninfected women. Induction of T-cells with appropriate homing properties is of interest for vaccine development, as HSV are primarily mucocutaneous pathogens. I therefore propose investigations of how HSV-2-specific CD4 T-cells traffic to sites of viral replication in the setting of natural infection. Lymphocyte migration is a multistep process including programming for homing during priming, loose adherence to vascular endothelium, integrin maturation, which can be triggered by chemokines and leads to tight adhesion, and finally extravasation and chemotaxis into the parenchyma. Adherence is mediated by selectins, integrins, and their ligands on lymphocytes and on vascular endothelium. Our lab has shown that HSV-2-specific CD8 T-cells selectively express CLA, a molecule related to a functional E-selectin ligand (ESL), and that vascular E-selectin is up-regulated in the dermis in genital HSV-2 lesions. New preliminary data show that HSV-2- specific CD4 T-cells express CLA and a functional ESL. We hypothesize that during antigenic priming, HSV- 2-specific CD4 T-cells are programmed for homing, expressing a specific "profile" of adhesion molecules and chemokine receptors that is related to the site of infection. We further hypothesize that maintenance of this program requires periodic re-stimulation with antigen. In Aim 1, we measure ESL expression by HSV-2- specific CD4+ T-cells in persons with chronic HSV-2 infection, emphasizing direct ex vivo studies. In Aim 2, we determine the profile of integrins and chemokine receptors expressed and active on HSV-2-specific CD4 T-cells. Functional assays for chemokine effects on integrin-mediated adhesion will be done to determine their impact on CD4 T-cell homing. In Aim 3, we will use adoptive transfer of CD4 cells in mice to determine if the site of immunologic priming controls the homing properties of resultant memory cells, and if so, how long this memory for homing lasts. Understanding of CD4 T-cell trafficking to skin in the context of HSV-2 infection should be broadly applicable in vaccine design for mucocutaneous pathogens.